The present invention relates generally to dynamoelectric machines and more particularly to improved methods and apparatus for inserting one or more windings into axially extending slots of a magnetic core of a dynamoelectric machine stator assembly.
Currently employed apparatus provide for automatic insertion of windings into the slots of a magnetic core. Exemplary automated apparatus for axial insertion of coils of windings into magnetic cores include U.S. Pat. Nos. 3,672,027 and 3,722,063 (Arnold), 3,579,818 (Arnold et al), 3,973,601 (Arnold et al), 2,432,267 (Adamson), 2,934,099 (Mason), 3,324,536 (Hill), 2,836,204 (Mason), and 3,528,170 (Duff et al); and U.S. patent application Ser. No. 14,538 (Fooyontphanich et al) filed Feb. 23, 1979. The entire disclosures of these patents and the patent application are incorporated herein by reference.
Windings for dynamoelectric machines generally comprise a plurality of coils formed from a plurality of conductor turns. As an example, one pole of a main winding may typically comprise a coil group of five coils (each comprising a number of turns) that are inserted into axially extending slots of a magnetic core of the dynamoelectric machine. The five coils may be referred to as coils 1, 2, 3, 4, and 5 of a given coil group or pole, with the lower the number designation of the coil the closer the spacing (i.e., the lesser the circumferential span) between the axially extending slots of the magnetic core into which a side portion of each coil is respectively inserted. Also, the larger the number of the coil designation the larger the coil. In any winding injection process it is desirable to complete the injection of the coils so that the coils are evenly spaced axially along the magnetic core. Such even spacing allows the coils to be subsequently evenly folded back against the end faces of the stator core.
The desired axial spacing of the coils is often hindered by two factors; (1) the coils that are inserted into the inner peripheral slots of the magnetic core pull up tight to the bottom face of the core before the remaining coils can be pulled into even axial spacing along the magnetic core, (2) the longer coils are pulled by the shorter coils during the insertion process creating an interengagement pressure between the coils hindering equal distribution of the longer coils. The present invention is primarily concerned with reducing the interengagement pressure created by the shorter coils pulling against the longer coils during insertion. Reducing the interengagement pressure allows for a more even spacing of the coils axially along the magnetic core upon completion of the insertion process. Reducing the interengagement pressure also permits further insertion of coils into stator slots and thereby allows for a longer slot separator wedge to be used.
Accordingly, a general object of the present invention is to provide new and improved methods and apparatus for inserting coils into a dynamoelectric machine stator which allows for a more even axial spacing of the coils within the stator.
A more specific object of the present invention is to provide new and improved methods and apparatus for axially inserting coils into a dynamoelectric machine stator while reducing the interengagement pressure between respective longer and shorter coils as the shorter coils are inserted into their axially extending slots.
A still further object of the present invention is to provide further insertion of the coils into stator slots and thereby allow for the use of a longer slot separator wedge.